Hi guys... I've been looking for the past few days now for a comprehensive reading regarding the 737NG's electrical systems. I have some pretty basic questions that aren't adequately answered (to my needs)by the famous UK Boeing 737 Aircraft Systems site. For example, it states there that the TR Unit converts AC into DC. However I'm such a leiman regarding these things that I needyet to learn the difference between AC and DC and why an aircraft needs such a TR unit. I'd also like to know what IDGs, buses and so on are. I can fly the plane alright but I'm embarassed by the fact that I don't know it's workings much like a doctor who doesn't know a thing about physiology. So if anyone can point me to where I can learn about these things I'd greatly appreciate it!Regards,Victorhttp://www.precisionmanuals.com/images/forum/800driver.jpg

http://www.smartcockpit.com/ has more detailed descriptions in their notes for you.

Thansk again Dave!http://www.precisionmanuals.com/images/forum/800driver.jpg

Hi Victor,just a few notes regarding basic electrical infos on aircrafts.First, DC is direct current, that is a current that flows always in the same direction. Typical DC current is provided by batteries and is generated by dynamos.AC is alternating current, that is a current that swithces back and fort many times a second (in aircrafts normally 400 Hz, that is 400 times a second).This is the standard current used in your home (110 or 220 V, 50 Hz). Typical AC current is generated by alternators (such as the one you have in your car).Since most electronics use DC, here's the need for TR (transormer/rectifier) unites, that is "black boxes" which transform AC current (generated, for example, by Integrated Drive Generators, IDG that take power from the rotating engines and generate AC current, they are alternators) in DC current to recharge the batteries and provide DC current.Buses are the electrical "mains" to which all electrical-powered users are connected.Hope this helps.Enrico

Thank you so much my friend, you have saved me hours of boredom of reading basic physics from High School. I sorta flunked that part and gave it up all together when I started going to Med school. Never thought I'd need it again. Let alone to fly a Boeing!Regards,Victorhttp://www.precisionmanuals.com/images/forum/800driver.jpg

You are welcome.It happens that I'm an aeronautical engineer, so these tech thingies are my daily bread (even if I'm not actually working in the aeronautical field).Best regards.

>You are welcome.>It happens that I'm an aeronautical engineer, so these tech>thingies are my daily bread (even if I'm not actually working>in the aeronautical field).>Best regards.Engineers....... I'm an A&P Mechanic...... Engineers....:(